[4] The oldest parish in Germany is on the North Frisian island of Nordstrand; its origins go back to the year 1654.

It was established by Dutch Ultrajectine Catholics from the Archdiocese of Utrecht employed to build dykes.

In Bavaria, Old Catholic parishes are particularly concentrated in areas where German refugees from Bohemia and Moravia settled after World War II.

In the traditionally Protestant areas of northern and eastern Germany, by contrast, parish boundaries are far larger, reflecting the diaspora situation there.

[3] The diocese has its cathedral at the Namen-Jesu-Kirche (Church of the Holy Name of Jesus) in Bonn, which was renovated by the state and provided to the Old Catholics for their use starting 2 June 2012.